WIP: Attempting to remove cfg in create_allocator_mapping

NOTE: IT DOESN'T COMPILE.  create_allocator_mapping doesn't have the
`<VM>` generic parameter, but the `NonMovingSpace` trait needs it.
There ought to be a way to work around it.

Author: wks

src/plan/mod.rs

@@ -31,6 +31,7 @@ pub(crate) use global::PlanTraceObject;
 mod mutator_context;
 pub use mutator_context::Mutator;
 pub use mutator_context::MutatorContext;
+pub(crate) use mutator_context::ReservedAllocators;
 
 mod plan_constraints;
 pub use plan_constraints::PlanConstraints;

src/plan/mutator_context.rs

@@ -439,7 +439,7 @@ impl ReservedAllocators {
 
     // We may add more allocators from common/base plan after reserved allocators.
 
-    fn add_bump_pointer_allocator(&mut self) -> AllocatorSelector {
+    pub(crate) fn add_bump_pointer_allocator(&mut self) -> AllocatorSelector {
         let selector = AllocatorSelector::BumpPointer(self.n_bump_pointer);
         self.n_bump_pointer += 1;
         selector
@@ -450,13 +450,13 @@ impl ReservedAllocators {
         selector
     }
     #[allow(dead_code)]
-    fn add_malloc_allocator(&mut self) -> AllocatorSelector {
+    pub(crate) fn add_malloc_allocator(&mut self) -> AllocatorSelector {
         let selector = AllocatorSelector::Malloc(self.n_malloc);
         self.n_malloc += 1;
         selector
     }
     #[allow(dead_code)]
-    fn add_immix_allocator(&mut self) -> AllocatorSelector {
+    pub(crate) fn add_immix_allocator(&mut self) -> AllocatorSelector {
         let selector = AllocatorSelector::Immix(self.n_immix);
         self.n_immix += 1;
         selector
@@ -506,20 +506,11 @@ pub(crate) fn create_allocator_mapping(
     // spaces in common plan
 
     if include_common_plan {
+        // TODO: This file currently contains information about all spaces (i.e. what allocator each space uses).
+        // We really should let each space reserve its appropriate allocator.
         map[AllocationSemantics::Immortal] = reserved.add_bump_pointer_allocator();
         map[AllocationSemantics::Los] = reserved.add_large_object_allocator();
-        map[AllocationSemantics::NonMoving] = if cfg!(not(any(
-            feature = "immortal_as_nonmoving",
-            feature = "marksweep_as_nonmoving"
-        ))) {
-            reserved.add_immix_allocator()
-        } else if cfg!(feature = "marksweep_as_nonmoving") {
-            reserved.add_free_list_allocator()
-        } else if cfg!(feature = "immortal_as_nonmoving") {
-            reserved.add_bump_pointer_allocator()
-        } else {
-            panic!("No policy selected for nonmoving space")
-        };
+        map[AllocationSemantics::NonMoving] = ChosenNonMovingSpace::reserve_allocator(&mut reserved);
     }
 
     reserved.validate();

src/policy/nonmovingspace.rs

@@ -3,7 +3,12 @@
 //! We can use Cargo features to choose one of `ImmixSpace` (default), `ImmortalSpace` and
 //! `MarkSweepSpace` as the non-moving space.
 
-use crate::{util::VMWorkerThread, vm::VMBinding, AllocationSemantics, Mutator};
+use crate::{
+    plan::ReservedAllocators,
+    util::{alloc::AllocatorSelector, VMWorkerThread},
+    vm::VMBinding,
+    AllocationSemantics, Mutator,
+};
 
 use super::space::{PlanCreateSpaceArgs, Space};
 
@@ -21,6 +26,8 @@ pub(crate) trait NonMovingSpace<VM: VMBinding>: Space<VM> {
     fn end_of_gc_nonmoving_space(&mut self);
     /// Call this in `common_release_func` when using this space as the non-moving space.
     fn release_mutator_nonmoving_space(mutator: &mut Mutator<VM>, tls: VMWorkerThread);
+    /// Call this to reserve allocator in `create_space_mapping`.
+    fn reserve_allocator(reserved: &mut ReservedAllocators) -> AllocatorSelector;
 }
 
 impl<VM: VMBinding> NonMovingSpace<VM> for crate::policy::immortalspace::ImmortalSpace<VM> {
@@ -43,6 +50,10 @@ impl<VM: VMBinding> NonMovingSpace<VM> for crate::policy::immortalspace::Immorta
     fn release_mutator_nonmoving_space(_mutator: &mut Mutator<VM>, _tls: VMWorkerThread) {
         // Do nothing
     }
+
+    fn reserve_allocator(reserved: &mut ReservedAllocators) -> AllocatorSelector {
+        reserved.add_bump_pointer_allocator()
+    }
 }
 
 impl<VM: VMBinding> NonMovingSpace<VM>
@@ -75,6 +86,10 @@ impl<VM: VMBinding> NonMovingSpace<VM>
         .unwrap()
         .release();
     }
+
+    fn reserve_allocator(reserved: &mut ReservedAllocators) -> AllocatorSelector {
+        reserved.add_malloc_allocator()
+    }
 }
 
 impl<VM: VMBinding> NonMovingSpace<VM> for crate::policy::immix::ImmixSpace<VM> {
@@ -113,6 +128,10 @@ impl<VM: VMBinding> NonMovingSpace<VM> for crate::policy::immix::ImmixSpace<VM>
         .unwrap()
         .reset();
     }
+
+    fn reserve_allocator(reserved: &mut ReservedAllocators) -> AllocatorSelector {
+        reserved.add_immix_allocator()
+    }
 }
 
 // Choose one concrete non-moving space implementation according to the enabled Cargo feature.